1. Field
The presently disclosed subject matter relates to semiconductor light-emitting devices including an LED chip, and more particularly to a reliable semiconductor light-emitting device having a favorable light distribution, which can emit a different colored light as compared to the light emitted by the LED chip.
2. Description of the Related Art
Semiconductor light-emitting devices using an LED chip as a light source have been developed, which can emit a different colored light from that of the LED chip in order to emit various colored lights. An example of such a semiconductor light-emitting device is disclosed in patent document No. 1 listed below and shown in FIG. 1. FIG. 1 shows a conventional semiconductor light-emitting device that is disclosed in Patent Document No. 1.
The conventional semiconductor light-emitting device can include: a semiconductor light-emitting chip 110 having top and bottom electrodes and a light-emitting surface 110a; an electrode pad 130 of the top electrode that is made by forming on an exposed portion 122 of the light-emitting surface 110a; a phosphor layer 120 including a transparent silicone and a phosphor that is formed on the light-emitting surface 110a except at the electrode pad 130; the bottom electrode of the semiconductor light-emitting chip 110 mounted on a die bonding pad; and the electrode pad 130 electrically connected to a bonding pad with a bonding wire 140.
In the above-described semiconductor light-emitting device, for example, when the semiconductor light-emitting chip 110 is a blue LED chip that emits a blue light, and the phosphor layer 120 is a yellow phosphor for converting blue light to a complementary yellow light, a part of the blue light emitted from the blue LED chip excites the phosphor layer 120 and converts it to yellow light, which can be mixed with other parts of the blue light emitted from the blue LED chip by means of additive color mixture. Thus, the conventional semiconductor light-emitting device can emit light having a white color tone.
FIG. 2 is a flow chart showing a manufacturing process for the conventional semiconductor light-emitting device that is disclosed in Patent Document No. 1. The process for manufacturing the conventional semiconductor light-emitting device includes: forming the phosphor layer 120 on the semiconductor light-emitting chip 110 (step 710); forming the exposed portion 122 on the semiconductor light-emitting chip 110 using photolithography (step 720); forming the electrode pad 130 on the exposed portion 122 of the light-emitting surface 110a (step 730); and bonding to the electrode pad 130 with the bonding wire 140 (step 740). In the above steps 710 and 720, the phosphor layer 120 can also be formed while allowing the exposed part 122 to expose the light-emitting surface 110a by a printing process.
However, the bonding wire 140 that is located on the semiconductor light-emitting chip 110 shown in Patent Document 1 may be peeled from the electrode pad 130 by vibration and shock. In order to prevent the bonding wire 140 from peeling from the electrode pad 130, it may be necessary in some cases to not have the phosphor layer 120 formed on the electrode pad 130. Therefore, a blue light (a blue light that is not wavelength-converted) that is not excited by the phosphor layer 120 at a portion close to the electrode pad 130 is directly emitted (hereinafter described as a leak of blue light) from the semiconductor light-emitting chip towards the outside. The leak of blue light may cause color variability in the color tone of light emitted from the semiconductor light-emitting chip 110.
A structure for preventing the bonding wire 140 from peeling from the electrode pad 130 by vibration and shock is disclosed in patent document No. 2 listed below. FIG. 3 is a cross-section view showing a conventional structure for protecting a bonding wire from vibration and shock. The conventional structure includes: circuit boards 206 and 207; a driving tape 205 located between the circuit boards 206, 207; a wire bonding pad 204; a bonding wire 203 bonded to the wire bonding pad 204; a soft molding material 202; and a hard molding material 201. However, the above structure does not prevent the leak of blue light because this conventional structure does not include a phosphor for converting a wavelength of light.
The above-referenced Patent Documents are listed below and are hereby incorporated with their English abstract in their entireties.    1. Patent document No. 1: Japanese Patent Application Laid Open JP2008-514027 (National Laid Open WO2006/036251: PCT/US2005/023874)    2. Patent document No. 2: Japanese Patent Application Laid Open S62-186553
The disclosed subject matter has been devised to consider the above and other problems, features, and characteristics. Thus, embodiments of the disclosed subject matter can include reliable semiconductor light-emitting devices using an LED chip which can be used under vibration and shock circumstances and which can emit a different colored light from that of the LED chip while preventing the leak of light from the LED chip device that is not wavelength-converted. The device can include a semiconductor white light-emitting device using a blue LED chip and can be configured to prevent the blue LED chip from leak of blue light and can also be configured to improve the brightness thereof.